Quill by Story Studio - Paint in virtual reality on an infinitely scalable canvas
Vectary - Vectary is a free, online 3D modeling tool and sharing platform.
Tilt Brush - Paint in spaces around you with Virtual Reality
threed.io - Generate custom 3D device mockups in your browser.
A-Painter - Paint in VR in your Browser
Poly API by Google - A free API for Poly. Development in 3D made simple.